package com.eastelsoft.smartiot.bssserver.util;

import java.security.MessageDigest;

//MD5算法返回数字型字串
public class MD5Encrypt {

    private final static String[] hexDigits = {
        "0", "1", "2", "3", "4", "5", "6", "7",
        "8", "9", "a", "b", "c", "d", "e", "f"};

    /**
     * 转换字节数组为16进制字串
     * @param b 字节数组
     * @return 16进制字串
     */
    public static String byteArrayToString(byte[] b) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++) {
            resultSb.append(byteToHexString(b[i]));//若使用本函数转换则可得到加密结果的16进制表示，即数字字母混合的形式
            //resultSb.append(byteToNumString(b[i])); //使用本函数则返回加密结果的10进制数字字串，即全数字形式
        }
        return resultSb.toString();
    }

    private static String byteToNumString(byte b) {

        int _b = b;
        if (_b < 0) {
            _b = 256 + _b;
        }

        return String.valueOf(_b);
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0) {
            n = 256 + n;
        }
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    public static String MD5Encode(String origin) {
        String resultString = null;

        try {
            resultString = new String(origin);
            MessageDigest md = MessageDigest.getInstance("MD5");
            resultString =
                byteArrayToString(md.digest(resultString.getBytes()));
        }
        catch (Exception ex) {

        }
        return resultString.toUpperCase();
    }
    
    public static String MD5Decode(String origin) {
        String resultString = null;

        try {
            resultString = new String(origin);
            MessageDigest md = MessageDigest.getInstance("MD5");
           
            resultString =
                byteArrayToString(md.digest(resultString.getBytes()));
        }
        catch (Exception ex) {

        }
        return resultString.toUpperCase();
    }

    
    
    
    
}
